1. Technical Field
The present invention relates to a tube unit, a control unit, and a micropump including the tube unit and the control unit both of which are attachable to and detachable from the micropump.
2. Related Art
A wriggle type pump is known as a device for transporting liquid at low speed. An example of the wriggle type pump includes a step motor as a drive source to rotate a rotor having a plurality of rollers. This rotor rotates along a flexible tube while turning the plural rollers to suck and discharge liquid (for example, see Japanese Patent No. 3177742).
This pump is produced by stacking a motor module having a step motor, and a pump module having plural rollers, a motor, and a tube.
According to the wriggle type pump disclosed in Japanese Patent No. 3177742, the tube is constantly closed by the rollers after manufacture. Thus, when the period from manufacture (assembly) until use is long, the restoration force of the tube decreases. In this case, sufficient liquid delivery accuracy cannot be secured.
Moreover, the pump produced by stacking the motor module and the pump module according to Japanese Patent No. 3177742 is difficult to reduce the thickness of the structure.
A miniaturized step motor can generate only small drive torque, and thus rotational torque of the rotor needs to be increased by using a speed reduction mechanism (speed reduction gear mechanism) having a large reduction ratio. Consequently, when a multistep reduction gear mechanism is used for this purpose, the size of the pump and the loss by the speed reduction increase.
Moreover, pinion and gear which engage with each other for attaching the stacked pump module and the motor module come to overlap with each other when the tooth phases do not agree with each other. In this case, the pinion and gear are broken.
Furthermore, it is known that the step motor generates electromagnetic noise. Thus, adverse effect may be given to peripheral devices, or the step motor may be affected by electromagnetic noise of the peripheral devices.